My ISP uses CGNAT and hence they are told me that, they cannot provide me with dynamic public IP and buy a static IP. Is there any way to get dynamic public IP from my ISP?

I have heard of PCP (Port Control Protocol). Is that a medium for overcoming the problem i mentioned above?

Please help me friends.


When your ISP is using CGN then it's unlikely that there is just one public IPv4 address. There will be a whole pool of public addresses that they'll be using for their customers. Whether they perform some "stability" by using a consistent public address for a customer cannot be answered here. You'll need to ask your ISP for that information.

My home connection (DS-Lite based) used the same public IPv4 address for up to one day, but the next day it would be a different address. Some time ago I noticed that the public address seemed more stable, but I'm fully aware that it may change at any time. Theoretically it might change for every single traffic flow…

If you want to see what public address is visible to a web server you can go to websites like http://ip4.me.

  • But here in my case, my public IP and WAN IP are different. – mcv Jan 24 '18 at 8:37
  • Your own WAN address is irrelevant when you're behind CGN, what is visible on the internet is the public address that is used in the final NAT box. – Sander Steffann Jan 24 '18 at 14:20
  • Is there any way to do port forwarding? I have tried to forward it doesn't work. – mcv Jan 25 '18 at 9:47
  • No, that's impossible with CGN – Sander Steffann Jan 25 '18 at 13:19
  • What will be the changes in their system when i purchasing a static public IP from ISP. How they can provide me a public IP since they are using CGN. Why should they can provide me dynamic IP with the same setup for static IP. Pardon me if i am wrong. – mcv Jan 29 '18 at 10:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.